Photograph-enlarging apparatus.



T. A. EVANPSJK 1.1. SALISBURY.)

PHOTOGRAPH ENLARGING APPARATUSI Patented May 14, 1918.

APPLICATION FILED MAY 23. ISM-.-

- 3 SHEETSSHEEI l. 42%

T. A. EVANS 1 L. A. SALISBURY PHOTOGRAPH ENLABGING APPARATUS.

APPLICATION FILED MAY 23. I914.

Patented May 14, 1918.

7 ZZZW T. A. EVANS 61 L. A. SALISBURY.

PHOTOGRAPH ENLARGING APPARATUS.

APPLICATION FILED MAY 2% I914.

Patented May14,1918.

3 SHEETSSHEET 3.

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UNITED STATES PATENT OFFICE.

THOMAS ARTHUR EVANS, or CHICAGO, AND LYNN A. SALISBURY, or From, ILLINOIS.

FHOTOGRAPH-ENLARGING APPARATUS.

-l- Specification of Letters Patent.

Patented May 14, 1918.

Application filed May 23, 1914. Serial No. 840,448.

To all whom it ma concern:

Be it known t at we, THOMAS ARTHUR EVANS and LYNN A. SALISBURY, citizens of the United States, residing, respectively, at Chicago, Cook county, and Elgin, Kane county, Illinois,'have invented certain new and useful Improvements in Photograph- Enlarging Apparatus, of which the following is a specification.

his invention relates to improvements in photograph enlarging apparatus and one of the objects of the same is to provide an improved apparatus which can be quickly, accurately and automatically adjusted to en large or reduce any negative, picture or obj ect to a predetermined ratio of enlargement or reduction.

A further object is to provide an improved device of this character havin means for automatically taking up the s ack or lost motionbetween moving parts.

A further object is to provide an improved device of this character having means whereby commercial variation in. focal lengths of specific lenses may be accommodated.

A further object is to provide an improved apparatus of this character which will be simple, durable and cheap in construction, and effective in operation.

To the attainment of these ends and the accomplishment ofother new and useful objects as will appear, the invention conslsts in the features of novelty, in substantially the construction, combination and arrangement of the several parts hereinafter more fully described and claimed and shown in the accompanying drawings illustrating the invention, and in which,

Figure 1 is a side elevation of an apparatus of this character constructed in accordance with the principles of this invention. 1

Fig. 2 is a view taken on line 2-2, Fig. 1.

Fig. 3 is a detail perspective view of the mechanism for accommodating the variations in focal lengths of the lenses.

Fig.4 is a detail view taken on line 44, Fig. 1. a

Fig. 5 is a view taken on line 55, Fig. 1.

Fig. 6 is a view similar to Fig. 1 of a modified form of the invention.

Fig. 7 is a view taken on line 7-7, Fig. 6.

Fig. 8 is an enlarged detail plan view of a portion of the negative and screen relative shifting apparatus.

Referring more particularly to the drawings 1O designates a supporting structure having on its top, side rails 11 upon which the p otograph apparatus is mounted. A screen or sensitive paper support 12 is mounted upon a carriage 13 supported on rollers 14 which run upon the slde rails 11 as tracks. Rack bars are supported by and extend lengthwise of the side rails 11 but are positioned to clear'the rollers 14.' The rack bars 15 mesh with pinion gears 16 which are connected by a shaft 17, the latter being journaled in suitable bearings in the carriage 13 so that the operation of a handle 18 attached to shaft 17 will cause the carriage 13 with its screen 12 to move backward or forward along the side rails 11.

The camera or projector 19 is mounted. on a carriage 20 having rollers 21 which also travel on the guide rails 11. Bellows 25 such as are commonly'used in the art of pho-- tography extend between the negative holder 26 of the camera 19 and the lens holder 22 which is mounted upon a support 23 rigidlyconnected with the support 10. The support 23 has mounted upon it two racks 57 into which mesh two pinion gears 56 attached to a shaft journaled in lens support 22 in such a manner that when the handle is turned the lens support 22 ma be adjusted backward or forward. The istance between the lens 27 and the negative or plate holder 26 may be varied by means of the handle 55 or by the handle 54 or by a take-upmechanism as will be described later, the bellows 25 being of such dimensions to permit uchadjustments as are necessary.

In making enlargements commercially it has been the practice to place the sensitive paper which is to receive the enlargement upon the su port 12 and to place the ne ative to be en arged upon the negative hol er 26 to then adjust the distance between the screen 12 and the lens and later the distance .between the lens and the negative holder until the desired size of enlargement and clearness has been secured.

With the present invention these two adjustments which have a definite relation to each other are effected automatically and simultaneously by the adjustment of one of the elements involved and in such a manner that wear and tear in co-acting parts of the apparatus is compensated for. In Fig. 5 mechanism is shown for accomplishing such adjustments. A shaft 28 having cup and cone bearings which are adjustable as shown at 29 and 30 has attached to it a disk 31, cam 32 and a pulley 55".

A flexible member 33 preferably in the form of a steel tape is connected at one extremity to the periphery of the disk 31 and extends over a pulley 3 1 located at one end of the supporting frame and is connected at the other extremlty to the screen 12. A turn buckle 36 may be provided in the tape 33 in order that the screen 12 may be properly positioned with respect to the lens 27 when such adjustment is found necessary. The.

tape 33 functions to rotate disk' 31, consequently the cam 32 whenever the screen 12 is moved toward the lens 27 When the screen 12 is moved in the opposite direction slack is taken up from the tape 33 by means of the weight 56 as will be explained later.

The cam 32 functions to move the negative support 26 toward or away from the lens 27 Whenever the pivoted shaft 38 hearing the disk 31, the cam 32 and the pulley 55 is rotated. The contour of the cam 32 is determined as follows:

A lens has two foci which have a definite relation to each other, these being termed the conjugate foci, for which the following formula holds true:

where p=the distance from the lens to negative. f=the focal length of the lens.

. nzthe number of enlargements.

We have converted this formula into a more convenient form for our work. To calculate the theoretical spiral from which the cam is constructed it is necessary to change the above straight line formula into a transcendental curve traced b a point which, while it revolves about a Xed point called the center, continuously approaches the center from the circumference of a circle having a radius of 2 or 2fd, according to a definite law. There ore let 6 equal the total number of degrees through which the cam 32 is to rotate per enlargement. Let in equal a 1-1 enlargement in degrees.

From the formula,

we have,

But I i g=specified enlargement or n.

For a 11 enlargement, p is the distance from the center of the spiral to its perim- Therefore In no case can 6 be less than a degrees as the curve breaks at this point for obviously it is impossible to make an enlargement less than 11 or reduction greater than 11. The negativev holder cannot be less than 2f and have the image holder or screen at 2/ and the reverse also'holds true. This formula holds true for any focal length lens, any diameter of enlargements through any degree of rotation about the center of the spiral. Therefore,

6 cannot be less than a degrees.

The limits of this spiral are f and 27'.

In other words the curve never goes beyond twice the focal length of any given lens away from the center 'of the spiral. Neither does it ever approach nearer the center of the spiral than the given focal given length of lens.

In constructing the cam 32 it is first necessary to calculate the theoretical spiral by the above formula with the following addition,

Where p=distance from the center of cam to the center of pin in roller 39 Where d=represents any constant, as it is obvious that we can add or subtract any constant from p and it will then p and all points on this curve will cause the pin in roller 39 to travel on exactly the same lines as the negative-holder travels. All that has been changed is the relation of the inner circle to its center. The relation of the two circles to each other remains the same. The difference in their radii is f. In other words, the spiral becomes sharper or flatter depending on whether we have deducted or added 11.

Then by well known methods, such as are shown in Elementary illechan-iwn by Stahl and Woods page 290, art. 154: copyright 1893 by DQIVan Nostrand Company the paralleled curve or working surface of the cam is I "plotted.

Referring to Fig. 3 a portion of cam 32 is shown 'in contact with anti-friction roller 39 which operates on connecting rod 37 sliding between guides 38 rigidly mounted on the supporting structure. A lever 40 is pivoted intermediate of its ends at 41 to the rod 37. and is preferably arranged transrersely with respect to it. This lever 40 has apin and slot connection 42- 13 with a fixed portion of the machine as for instance, the side rail 11. This pin and slot connection is provided to maintain a straight line motion of the camera carriage 20 at all times. Rigidly mounted upon lever 40 are bearings 44 in which is journaled a screw 45 operated by an adjusting handle 46. Threaded upon the screw 45 is a nut 47 pivotally connected to a slide-49 at 48. The slide 49 moves in guide-ways 50 rigidly connected to the carriage of the camera 20, The compensating mechanism mounted on lever 40 is used to "correct variations in the focal length of lenses of any specified focal length. For instance, a lens designatedby a manufacturer as having a six inch focal length may as a matter of fact have a focal length anywhere from 5% inches to 6.2; inches.

The correction of such variations is accomplished by simply adjusting the slide" 49 with respect to lever 40 by means of handle 46 which rotates the screw 45 to vary the position of the nut 47 relative to the pivot 41 of the lever, thereby rendering it possible to vary the travel or movement of the slide 49 without effecting the relative movements of lever 40 and the connecting rod 37.

\Vhen the shaft 28 is rotated in one direction, the cam 32 acting on roller 39 forces the connecting rod 37 together with the lever 40 and consequently the camera 19 away from the lens 27 and if the shaft 28 is rotated in the opposite direction, the camtends to be withdrawn from contact with roller 39, but this is prevented by a take-up mechanism comprising in the present form of the invention, a flexible member 50, one end of which is anchored to a pulley rigidly connected to shaft over pulley 53 and pulley 57 which supports weights 56, pulley 52 and is anchored at the other end to lever 40 at 51 or it may be anchored to the camera carriage proper. The pulley 57 and weight 56* are arranged to form a loop 54 in flexible conductor 50 so that the weight may function to con stantly keep the lever 40 in operative connection with the cam 32 through the medium of'the connecting rod 37. It will be manifest from the foregoing description that when the screen 12 is moved toward the lens 27 by means of the handle 18 the tape 33 is unwound from the disk 31 and the shaft 28 is caused to rotate the cam 32. This in turn forces the lever 40 and consequently the camera 19 with its plate holder 26 away from the lens 27. During this operation the weight 56 is raised. When the screen 12 is moved away from the lens 27 tension on the tape 33 is relieved and the weight 56 is permitted to act on flexible tape 50 to pull the lever 40 and consequently the camera 19 with its plate holder 26 toward the lens 27, at all times keeping the connecting rod in close contact with the cam 32 causing it to rotate and take up all slack in tape 33. The

28 and passing screen 12 and the plate holder 26 therefore moves in the same direction relative to the supporting frame 10 but at different speed and they move in opposite direction with re-= lation to the lens, that is, when the screen 12 is moved towardthe lens, the plate holder 26 is moved away from it and vice versa.

An indicating mechanism of any desired type or configuration may be provided for indicating the proper position of the paper support or screen. 12. A simple and efiicient indicator embodies a cylinder 51, which is rotatably mounted, preferably along the side of one of the rails 11. This cylinder 51 .is provided with a series of graduations 52 ,of the screen will simultaneously and relatively adjust the negative holder 26.

The proper initial adjustment of the screen 12 is obtained by the adjustment of the turn buckle 36 and the proper adjustment of the negative holder 26 on the other side of the lens 27 is obtained by means of adjusting the screw 54 which is connected with the camera body to adjust the latter with respect to the carriage 20.

The diffusion adjustment of the lens is obtained by means of a shaft 55 journaled in suitable bearings in the lens support 22 and to which shaft gears 56 are connected which mesh with racks 57 carried by the support 23, and as is usual in devices of this character.

' In the form of the invention, shown in Figs. 6 to 8, the relative adjustments of the screen or paper support 12 and the negative support 26 with relation to the lens 27 are obtained in a slightly different manner, in that the disk 31 is dispensed with and in lieu thereof, there is provided a gear 58 which meshes with teeth 59 carried by a floating rack 60, the latter movable in guides 61, and with the teeth of the rack 60 meshes a gear 62 carried by the shaft 17. The gear 62 is provided with a greater num ber of teeth than the gear 16, as for example, the gear 62 may be provided with one hundred and, twenty teeth while the gears 16 may be provided with one hundred, so that when the handle 18'is operated to rotate the shaft 17 to move the screen or paper support 12 toward the lens 27, the gear 62 will move the floating rack 60 in the opposite direction at a different rate of speed and this movement-of the rack 60 will through the medium of the teeth 59 rotate the gear 58 meshing therewith, which in turn is connected with the cam 32, to operate the latter clockwise in the manner simi- I the cam 32 counter clockwise so as to permit the negative holder 26 to be adjusted toward the lens 27 and this movement of the negative holder 26 will be efiected through the medium of the flexible member 63 which is anchored as at 50 and passes over a pultive that is too dense to see through, to focus ley 65 with aweight '66 secured to the free end of the flexible member, thereby not only causing the negative holder to be returned but to automatically take 'up'any slack or lost motion between the parts.

In order to insure that the parts main in their adjusted positions, any suitable locking or retaining mechanism may be. provided, and a simple and eficient device for this purpose comprises a nut or collar 67 which is mounted upon the shaft 17 preferably adjacent the outer face 68 of the carriage 13, to engage the threads 69 on the shaft, so that by rotating the collar, it may be forced against the face 68 of the carriage to frictionally bind the shaft 17 and the gears connected therewith against rotation.

When it is desired to effect adjustment, all

that is necessary is to give the collar 67 a siligpt turn upon the shaft 17 to release the s a t.

From the above description it is thought that the operation of this device will be clearly understood, but briefly stated it is as follows:

The lens holder is secured in position with respect to its support and thenegativ'e' 26 and element 20 are initially adjusted with respect to each other, and according to the 7 focal length of'the lens, and when the aparatus is once set, the desired enlargement 1s obtained and the parts are positioned with respect to each other by the operation of the element 18. This causes the elements 12 and 26 to be relatively and 'simultaneousl adjusted with respect to each other an also with respect to the lens, until thelparts are positioned to secure the desired size of enlargement.

Should there be any variation of the working focal length of the lens of an specified focal len h, for the use of whic the apparatus has een set, this variation in the working focal length of such lenses may be compensated for by the adjustmentof the adjustable connection 49 with the element 20, through the manipulation of the element 26, the screw 45 and nut 47.

be employed for reducing purposes andall 1 that would be necessary in this event would be to reverse the position of the sensitive paper support and the projector.

Attention is called to the relative p'ositionsof the arm 40 and thecam 32 in Figs. 2 and 7 in which it is shown that the cam is not at the limit of its travel when the arm 40 is perpendicular to the connecting rod 37. The location of the pin 42, to secure the proper relation between the arm and cam may be determined by trial. After its proper location has been found, it need not be changed although lenses of different focal length are used. 2

While the preferred form of the invention has been herein shown and described, it is to be understood that various changes may be made in the details of construction and in the combination and arrangement of the several parts without departing from the spirit of this invention.

We claim:

1. A device of the character described embodying projecting apparatus comprising a lens, a negative holder and a screen disposed to receive rays projectedfrom the negative, holder, a cam and roller device for simultaneously changin the positions of the screen and negative ho der relative to the lens, a connecting member between the screen and cam whereby motion of the screen is transmitted to the cam and roller device, and an adjusting device for I(iompensating varia tions in lenses of speci ed focal length.

2. A device of the character described embodying projecting apparatus comprising a lens, a negative ho der and a screen disposed to receive rays projected from thenegative holder, a cam 'and roller device including connectingv members for simultaneously changing the position of the negative holder relative to-the lens upon movement of the screen, an adjusting device for compensat ing variations in lenses of specified, focal length, and a flexible member and weight frame, a projecting a and screen, and a slidable rod connecting the cam to the negative holder pivotally.

4. In photograph enlarging apparatus, the combination with supporting apparatus, a lens, a plate holder and a screen disposed to receive rays projected from the plate holder-onto the screen, of adjusting mechanism comprising a pivotally mounted cam, a connecting rod in Contact therewith controlling the movement of the plate holder, a

member connecting the screen and cam, and a flexible member holding the cam and plate holder in contact serially whereby a movement of the screen causes a relative movement of the plate holder.

5. In photograph enlarging apparatus, a supporting frame, a projecting lens, a plate holder, a screen disposed to receive rays projected from the plate holder, a cam the screen, adjusting means for simultanemounted pivotally to adjust a connecting rod, a member for turning the cam upon movement of the screen in one direction, tension means for turning the cam in the opposite direction upon movement of the screen in the opposite direction, a lever pivotally supported at one end and pivotally attached to the connecting rod, means for adjusting the plate holder upon the lever and means for adjusting the plate holder transversely of the lever.

6. An apparatus of the character described, embodying a projecting lens, a negative holder ad ustable toward and from the lens, a screen disposed to receive rays projected from the plate holder, means for adjusting the screen with respect to the lens, and means responsive to the movement of ousl and relatively adjusting the negative hol er, the screen and holder moving in the same direction with relation to each other but in opposition with respect to the lens, the said responsive means including a cam and roller mechanism and a take-up device for automaticallycompensating lost motion between movable parts also functioning as an actuator in one direction for the negative holder adjusting means.

7. A device of the character described embodying a projecting apparatus comprising a lens and a negative holder on one side thereof and adjustable with respect thereto, a screen on the other side of the lens and adjustable with respect to the lens, an actuator for moving the screen toward and from the lens, and means connected with the negative holder and controlled by said actuator for simultaneously and automatically imparting to the negative holder a relativeadustment with respect to the lens, the second recited means embodying a cam freely movaway from the lens, means responsive to the adjustment of the screen for simultaneously and automatically impartingto the negative holder a corresponding relative adjustment, the said means embodying a cam, an element shiftable by the'cam, said element connected with the negative holder and adjustable with respect thereto, and means tending normally to hold the said element and cam in operative relation.

9. A device of the character described embodying a lens, a screen on one side thereof movable toward and away from the lens, operating means for the screen, a negative holder on the other side of the. lens movable toward and away from the lens, a cam and roller device whereby said negative holderis responsive in its movements to the movement of the screen, and means for compensating the variations in focal lengths of specified lenses, the last said means embodying a swinging element, 40, and a slide, 49, adjustably pivoted between the swinging element and the negative holder.

10. A device of the character described embodying a lens, a screen, a negative holder, said screen and holder being movable toward and away from the lens and adjustable relative to each iother, means whereby one Will be automatically and simultaneously moved toward and away from the lens \by the movement of the other, and freely adjustable means whereby,

the extent of the movement of the screen a lens, a plate holder and a screen disposed to receive rays projected by the lens, from the plate holder, of means for moving said screen along the frame, adjusting mechanism for moving the plate holder upon movement of the screen and relative thereto, said means comprisinga vertically pivoted cam, aflexible member, a rod in constant contact with said cam and pivotally connected through an adjustable swinging element with the plate holder.

In testimony whereof we have signed our names to this specification, in-the presence of two subscribing witnesses, on this 21st day of May, A. D. 1914.

THOMAS ARTHUR EVANS. LYNN A. SALISBURY.

Witnesses:

E. K. LUNDY, JR., J. H. JooHUM, JR. 

